While pre-existing health conditions can impact the overall success of weight-loss surgery (for instance, patients with type 2 Diabetes typically lose less excess body weight after surgery), studies have shown that many ailments linked to obesity are either improved upon or fall into remission after a successful procedure. For instance, a 2000 study performed on 500 weight loss surgery patients showed that nearly 96% of health conditions associated with obesity - such as high blood pressure, depression, sleep apnea, back pain and diabetes - improved greatly following loss of excess weight and long-term commitment to diet and exercise.